Oops, it doesn't look like 'yuu day' is a national day..

Other days

pampering

Pampering Day
buddy

Buddy Day
my little pony

My Little Pony Day
donate your hair

Donate Your Hair Day
blanket fort

Blanket Fort Day
kale

Kale Day
one

One Day
gallery

Gallery Day
kiss a ginger

Kiss A Ginger Day
cat girl

Cat Girl Day